Data concerning the chemical, physical and biological properties of carcinogenic N-nitroso compounds have been collected. Specific emphases have included (a) development of new or improved synthetic methods useful in carcinogen chemistry, and preparation of novel nitrosamines and related compounds for chemical and biological studies; (b) the biological chemistry of nitrosamines, both in vivo and in vitro, with special attention to the properties of suspected metabolic intermediates, as well as to the rate-modifying effects of deuterium substitution; (c) mechanistic studies on N-nitrosation reactions of environmental interest, particularly those accelerated by electrophilic species, including transition metal complexes; (d) chemical reactivity investigations, especially those aimed at developing decontamination and disposal methods useful for controlling the hazards associated with carcinogenesis research; and (e) determination of the structures and stereodynamic properties of various nitrosamines, nitrosating agents, and nitrosatable precursors, using methods such as X-ray diffraction, circular dichroism, and nuclear magnetic resonance spectrometry. Possible implications of this work with respect to the overall goal of human cancer prevention are sought.